Money is kind of in a weird place right now. In the early game it's almost impossible to earn enough to afford food and rent, but once your corruption creeps up a few notches and you start letting the disgusting nerd stare at your ass in the diner money becomes no problem. The first couple of weeks are kind of dull as you just focus on grinding corrupting and keeping food on the table.
So, you start off buying 10 ramen and after Saturday's trip to the beach you have $29. The cheapest school lunch is $3 (and given your energy, you shouldn't be paying more than that at this time) so you easily have enough money to get through the first week. If you work at the diner the minimum daily pay is $20, but it is pretty easy to make $5 in tips. The first Friday the rent doesn't seem to be due, so by Sunday the 10th when you need to buy more ramen you should have about $139. Let's say you spend $28 on 14 packets of ramen, bringing you to $111.
At this point you probably also have increased your max energy to 10.
The price of food in the not-walmart is $2,$10,$20,$35.
The price of lunch at the school is $3,$10,$15,$20.
So for the higher energy foods, the school lunch is cheaper than non-walmart, but for lowest energy ramen is the cheapest.
So now you get 3 energy from ramen, 2 energy from resting during class, and buy the $10 school lunch for another 6 energy to max out your 10 (and can burn 1 energy talking to pizza girl at not-walmart before going to school.)
Whether you burn 5 energy or 10 energy at the diner doesn't really matter, so serve the otaku and sweep outside, then go home to study/dance or just carry over unused energy to the next day. If you want you can even keep spending $3/day on school lunch and using only 5 energy at the diner. I think you should be getting about $27 to $31 per day at the diner during week 2.
So by the time the landlord knocks on Friday the 15th you should have no money problems paying the $150, but even if you do you just go into deficit. If you spent your time exploring places other than the diner and end up in debt, it takes no energy to start work at the diner and pick up that $20/day paycheck to start digging your way out. I don't see how money is an issue even early on.
Of course, there are cheat tools like the save editor, as well as exploits in both the android and pc versions to perform tasks at the diner like serving the otaku infinity times on day 1 until Chloe is the sluttiest slut that ever slutted.
Although now you've got me wondering... just how long could I play this game while trying to keep Chloe a total Prude. It would mean skipping almost all of the content, but might be as fun as playing a Pacifist in a Fallout game.